1. Field of the Invention
The present invention relates to an apparatus for, and a method of, transferring an image to a substrate. More particularly, the present invention relates to an apparatus for, and a method of, transferring at least one image to at least one substrate having a planar and/or curved surface such as, for example, a complexly curved surface. A flexible membrane, having an image printed thereon, is shaped by at least one forming fixture into a complementary shape to the substrate. A means to transfer the image from the shaped membrane to the substrate is provided.
2. Discussion of the Related Art
Various methods of transferring an image to a substrate have long been known. These methods have also included transferring images to substrates having flat, curved and uneven surfaces. The known methods are limited in their ability to transfer a high-quality image to a substrate of a particular size, having complex curves, having radii of a particular value, and/or to transfer the image to the edge of the substrate.
Examples of conventional image transfer apparati and methods are disclosed in, for example:
U.S. Pat. No. 6,276,266 teaches a pad printing system utilizing a programmable digital color printer for applying multicolor images to curved objects. The ""266 patent, however, does not teach or suggest the use of a forming fixture or a deformable membrane for transferring an inked image.
U.S. Pat. No. 5,921,177 teaches a pad printing machine having a print moving plate moveable back and forth and a printing pad moveable up and down, allowing the printing pad to print on an object while the print moving plate moves forward. The back and forth and up and down movement is controlled by a double-sided cam and roller system. The ""177 patent does not teach or suggest the use of a forming fixture or a deformable membrane for transferring an inked image. Further the control of movement of the various components of the present apparatus are controlled in a manner substantially different from that disclosed in the ""177 patent.
U.S. Pat. No. 5,694,839 teaches a method and apparatus for printing images around cylindrical items, the apparatus including a gravure plate, a flexible ink transfer pad for receiving an ink image from the gravure plate and transferring the image onto a flat silicon ink transfer plate, and rolling the cylindrical item in a continuous operation across the transfer plate, causing the desired pattern to be printed on the cylindrical item. The ""839 patent does not, however, teach or suggest the use of a forming fixture.
U.S. Pat. No. 5,088,401 teaches a method and apparatus for a moveable printing plate having a detector which senses initial contact between the printing plate and a workpiece in order to accommodate variations in thickness of workpiece while purportedly ensuring uniformity of the pattern printed on such work piece. The ""401 patent does not, however, teach or suggest the use of a forming fixture or a deformable membrane for transferring an inked image.
U.S. Pat. No. 5,054,390 teaches a method of creating large differences in the ink affinity of deformable, silicone rubber printing pads by utilizing different catalysts in the curing of the rubber. The rubber pads are utilized to transfer an inked image from an intermediate surface to an article. A method and apparatus for printing utilizing the pads having varying ink affinities is also disclosed. The ""390 patent is silent, however, on how membranes are deformed to conform to the shape of a substrate surface.
U.S. Pat. No. 4,896,598 teaches a process for printing an image on the surface of an article by applying a thixotropic thermal curable ink comprising a pigment and a catalyst to a printing plate having a recess in the form of the image to be printed. The ""598 patent does not teach, however, the use of a forming fixture or a deformable membrane for transferring an inked image.
U.S. Pat. No. 4,060,031 discloses a method and apparatus for printing materials wherein a matrix material has depressions in the shape of the image to be printed, which depressions are filled with ink. A printing pad having a surface normally repellent to ink is pressed onto the inked matrix causing the image to be transferred to the pad and thence from the pad to the surface of the article to be printed. The ""031 patent does not, however, teach the use of a forming fixture.
Accordingly, it would be advantageous to have a method to transfer a high quality image onto a substrate by printing on a flat membrane, and subsequently shaping the membrane with a forming fixture to conform with the surface of the substrate and transferring the image thereon through the application of pressure. This method would not be limited by the size or shape of the substrate upon which the image would be transferred.
The present invention is an apparatus and method for transferring a high-quality image to a substrate having a surface. The surface may be substantially planar, curved or a complexly curved surface such as, for example, the inside or outside surface of a concave substrate, a convex substrate, or a compound substrate.
In an embodiment of the invention, a membrane is located in a print station where an image is printed on the membrane using a pigment-containing material. If required, during the image transfer steps described in more detail below, the print station can simultaneously maintain the pigment-containing material in a print-ready condition by selectively printing on a medium at predetermined times.
The printed membrane is moved to a transfer station having at least one forming fixture and at least one substrate fixture. The substrate fixture is removably connected to a means for locating the substrate fixture adjacent the printed membrane. A separate substrate fixture for each substrate having a particular shape and curvature is attached to the locating means.
One or more forming fixtures shape the printed membrane into a complementary shape to the substrate. The forming fixture is designed to shape the entire membrane, or portions of the membrane, for substantially simultaneous or successive contact with the substrate to transfer at least one image. Pressure is added to the substrate fixture/membrane/forming fixture combination to effect the transfer. After the image is transferred to the substrate, the pressure is released. The substrate having the transferred image thereon is removed from the substrate fixture. Where layers of images are desired, where images are desired in more than one location, and/or where a different pigment-containing material is desired on the substrate, different portions of the first membrane or, at least a second membrane is used.